The production of semiconductor components requires cleanliness, such as control of particles, impurities, or foreign matter. The presence of these particulates can affect the yield of good devices within the processed wafers. Thus the transport of these wafers is typically carried out in special transport container, such as cassettes, carriers or trays, as well as closable or sealable containers or boxes, including Front Opening Unified Pod [FOUP], Front-Opening Shipping Box [FOSB], Standard Mechanical Interface [SMIF] pods or boxes. The FOUP typically possesses comblike guidance at two facing long sides for supporting the wafers, and can be closed with a removable cover. Without the cover the FOUP is a hollow container having a pot-like basic form with a rectangular surface area. In addition to wafers, reticles are also stored in reticle carriers, which are stored in a reticle stocker. The reticle carriers are transported to the lithography tool when needed for mask exposure.
The FOUPs and reticle carriers need to be cleaned occasionally to maintain the standard of cleanliness required in processing semiconductor wafers. The cleaning process can be performed in special cleaning and drying equipment. With increasing requirements for cleanliness, the number of cleaning cycles in the modern semiconductor factories rises, together with increased requirements for cleanliness. For example, it is desirable to clean a FOUP after each individual use in order to prevent, for example cross contamination from one wafer load to the next.
Thus it is desirable to shorten the time needed for a complete cleaning of the FOUPs. Furthermore, it is also desirable to keep cleaning consumption as small as possible, especially in view of the increased cleaning cycles. On the other hand, the cleaning must be very thorough in order to fulfill the cleanliness requirements of modern semiconductor factories.